You can DC into AC without any R. L or C components at all. Use d to have a valve car radio which used a mechanical "chopper" to switch DC at a high rate and convert battery DC to Ac for the High voltage on the valves (tubes, for you guys).
The points ignition system also converts DC to AC (although pulsed). So you see there are a few ways to convert DC to AC without electronics.

It's not possible using just basic passive components. But the most basic form of conversion from DC to AC that I can think of (not using elaborate circuitry) using a dynamotor to change DC to AC would work.

I'm not highly familiar with the process, so somebody correct me if I'm wrong, but applying a DC voltage to a stator or rotor will induce an alternating voltage in the opposing rotor or stator of a spinning motor.. Of course the motor needs to be spinning at 60 Hertz to produce a pure 60 Hz sine waveform. Given that basically you've created an alternator - that sine wave would be a pure sine wave. But then you're limited to the amount of current the alternator could produce. In fact, your automotive alternator is basically a dynamotor. The only difference is instead of using an electric motor to spin the alternator you're using a gasoline engine to spin it. Then it gets rectified back to DC to charge the battery and power the electronics.

If by passive components you mean wire, then yes. Before the vacuum tube was invented, high frequency radio carriers were created with a motor-generator set, a DC motor with a mechanical governor driving a mult-multi-multi-pole AC generator. This is what made the first voice radio broadcast in 1906. Technically, all passive components.

But to answer the question you're really asking - no. A circuit with sustained oscillation requires a circuit gain of at least 1.000, and all passive components have loss. In terms of energy going through the circuit, there is no combination of 0.9 this and 0.999 that that is greater than 1. It's that whole first law of thermodynamics thing.

This is what made the first voice radio broadcast in 1906. Technically, all passive components.

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Technically, a dynamotor is not a passive component. It's active by the nature of being driven by a motor. You're converting DC into mechanical energy then using that mechanical energy to turn an alternator, producing AC. At whatever frequency you produce, it is still AC.

Back in high school our teacher demonstrated a dynamotor for us. Allowed us to play with it. Boy did I get bit! I don't remember the voltages being generated, but it's anything BUT passive. True, if you look at it from the viewpoint of just being a series of coils - spinning and stationary, that is pretty passive. But the act of using mechanical force to generate an alternating signal is "Active".

OK. Back to the question at hand. AC to DC can be as simple as a diode and a capacitor. DC to AC can be a sine wave oscillator, a 555 timer, an inverter, or a chopper, but none of them are as simple as a couple of diodes and a capacitor. You can call a dynamotor active or passive, but it's still a lot more complicated than a couple of diodes and a capacitor. There's your bottom line. DC to AC is always more complicated than 2 or 3 passive components.

I know DC can be turned into AC. I am just talking about basic passive components. Thanks.

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Turning DC into AC is as simple as offsetting DC voltage, and can be done with nothing more than passive components. Any oscillating wave-form (even a square-wave) becomes AC when DC voltage is offset negatively for a portion of the wave-forms amplitude.